Fix indexing of binary attachments for proxies in Elasticsearch

Proxies cannot be found which a fulltext search on a keyword from a binary attachment (like a Word document)

Steps to reproduce:

1. create a MS Word file with the word "flower" inside
2. create a File document in the Workspaces with this MS Word file
3. Publish the File document to the Sections
4. Go to the Search tab > NXQL search
5. the query

   select * from Document where ecm:fulltext = 'flower' and ecm:isProxy = 1

   will return no result

nxql_query should be part of the overriden page providers using Elasticsearch